<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    div {
      font-weight: 700;
    }
    h1 {
      font-weight: 400;
    }
  </style>
</head>
<body>

<div>这是div</div>
<h1>一级标题</h1>

</body>
</html>
